Antimicrobial use and resistance in Helicobacter pylori infection

Researchers, in the latest issue of the Annals of Internal Medicine, find that previous use of macrolides and metronidazole is associated with Helicobacter pylori resistance.

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The relationship between previous treatments and infection with drug-resistant Helicobacter pylori is unclear.

In this study, researchers from Alaska, USA, determined whether previous use of antimicrobial agents predicted the subsequent antibiotic resistance of H. pylori. They also evaluated whether resistance influenced treatment outcome.

The team assessed 125 adults infected with H. pylori.

They reviewed patients' medical records, looking for antimicrobial agents prescribed in the 10 years prior to diagnosis with H. pylori infection.

The team also evaluated the antimicrobial susceptibility of H. pylori isolates by using agar dilution.

A cure was determined using urea breath tests 2 months after treatment.

Clarithromycin resistance is associated with previous use of any macrolide antibiotic.

Annals of Internal Medicine

Of the 125 patients, 30% had H. pylori isolates resistant to clarithromycin and 66% had isolates resistant to metronidazole.

The researchers determined that clarithromycin resistance was associated with previous use of any macrolide antibiotic, while resistance to metronidazole was associated with previous use of metronidazole.

Furthermore, the odds of isolates being resistant to clarithromycin increased with the increasing number of courses of macrolides received.

In patients treated with clarithromycin-based regimens, the team found that treatment failed in 77% of those with clarithromycin-resistant H. pylori, and in 13% of those with clarithromycin-susceptible strains.

Dr Brian McMahon's team concluded, "Previous use of macrolides and metronidazole is associated with H. pylori resistant to these antimicrobial agents".

"Clarithromycin resistance is associated with a greater risk for failure with clarithromycin-based treatments".